It’s time for some fun under the sun, but before you head out, make sure your skin is protected. While the sun sets the mood for a great beach vacation, it also damages your skin through UVA rays, which cause premature aging, and UVB rays, which cause sunburn.

It’s not just a matter of picking any old sunscreen off the shelf and slathering it on while you’re lying on the sand. First, you have to decide between chemical or mineral sunscreen. Then you have to know the proper way to apply it.

The difference between chemical and mineral sunscreens

Chemical and mineral sunscreens both provide sun protection but they have different ways of doing it.

Chemical sunscreens are the ones you’re probably used to. As the name connotes, this type of sunscreen contains chemicals like avobenzone, oxybenzone, and octinoxate. It works by absorbing UV rays, breaking them down through a chemical reaction, and releasing heat. Some people, particularly those with sensitive skin, may have an adverse reaction to the chemicals; the Environmental Working Group cautions that oxybenzone may have possible photoallergenic or allergenic effects.

Does this mean those who can’t tolerate chemical sunscreens are doomed to spend their days in the dark? That’s where mineral sunscreens come in. Sometimes referred to as physical sunscreens, mineral sunscreens contain minerals like zinc oxide and titanium oxide and are better for sensitive skin—so everyone can have their day in the sun.

Mineral sunscreens work by reflecting UV rays, instead of absorbing them. It’s akin to a white surface reflecting light; however, the sunscreen may turn your skin into a literal white surface, giving you a white cast because the minerals are made up of larger molecules.

This discourages some people from using mineral sunscreen, even if they’re better for sensitive skin. The good news is new technology can break down the minerals into smaller molecules, effectively eliminating the white cast. There are no studies as of yet to show that these smaller particles, some classified as nanoparticles, have negative side effects.

Which one is more effective?

Both types of sunscreen are effective for sun protection, as long as they’re applied properly. The American Academy of Dermatology gives the following guidelines for applying sunscreen:

Put it on 15 minutes before you go out into the sun to give your skin time to absorb it. Otherwise, you risk getting a sunburn. (Take note that mineral sunscreens, especially those without nanomolecules, take a bit more time and effort to put on because of the thicker consistency.)

Use about one ounce, which is enough to fit your palm.

Rub it thoroughly into your skin, taking care to cover all exposed parts (including your ears, the tops of your feet, and, if you have thinning hair, your scalp). Ask someone to put sunscreen for you on hard-to-reach areas like your back.

An additional tip: Look for a sunscreen marked “broad spectrum.” This means that it blocks both UVA and UVB rays. Also consider sun protection factor, or SPF, which protects you from UVB. The minimum SPF for sunscreens is typically 15 (which blocks 93% of UVB rays) but go for at least 30 (which blocks 97% of UVB rays). SPF50 blocks 98% of UVB rays, but anything higher than that doesn’t offer a significant increase in protection. There is no sunscreen that blocks 100% of UVB rays.

Going beyond skin protection

If you want to go beyond skin protection and consider environmental impact, then mineral is the way to go. Studies have shown that some ingredients of chemical sunscreens, specifically oxybenzone and octinoxate, are harmful to the environment.

When you go swimming or snorkeling, the sunscreen washes off and seeps into the ocean, finding its way to coral reefs. (It also washes off when you shower and eventually ends up in the ocean.) The chemicals in chemical sunscreen have been found to cause coral bleaching, which may lead to coral death.

Given the importance of coral reefs in marine ecosystems, fish communities, and the human communities that depend on them for both fishing and tourism, a reef-safe sunscreen is the conscientious choice. Something to consider when gauging chemical vs. mineral sunscreens. (All Good Sunscreen Sport, Derma E Baby sunscreen, and Derma E Face Sunscreen are all reef-safe sunscreens and are available at Healthy Options.)